Vortex pressure control device



219" 121 *1 mun uw June 11, 1968 E. A. PlNsLx-:Y ET AL 3,388,235

VORTEX PRESSURE CONTROL DEVICE Filed Deo. l, 1965 United States PatentOce 3,333,235 Patented June 11, 1968 3,388,235 VORTEX PRESSURE CONTROLDEVICE Edward A. Pinsley, Glastonbury, and Allan P. Walch,

Manchester, Conn., assignors to United Aircraft Corporation, EastHartford, Conn., a corporation of Delaware Filed Dec. 1, 1965, Ser. No.510,910 8 Claims. (Cl. 219-121) This invention relates to pressurecontrol devices such as can be used with workpiece out-of-vacuumelectron beam welders in which it is desired to establish a low pressureregion in the vicinity of an orifice or between an orifice and asurface.

More specifically, this invention relates to out-ofvacuum working orwelding with electrons or charged particles wherein the electron beamitself must be generated in a vacuum or low pressure environment.

It is an object of this invention to provide a pressure control in theform of a gaseous barrier between the point of emission of chargedparticles used in working materials and the workpiece itself. One formof such a device is disclosed in Patent No. 3,156,811, issued November10, 1964 to Frank W. Barry and entitled Gaseous Sealing Means in anApparatus for Working Materials by a Beam of Charged Particles.

The above object and the means for achieving it will be readily apparentfrom the following description of the drawing in which:

FIGURE 1 is a schematic illustration of an electron beam gun and thevortex pressure control according to this invention.

FIGURE 2 is an enlarged detail illustration showing the beam emittingregion of the apparatus.

FIGURE 3 is a modification of the FIGURE 2 arrangement.

FIGURE 4 is a transverse section of FIGURE 2 or 3 illustrating thevortex producing chamber.

Referring to FIGURE l, an evacuated beam generating chamber 10 is shownas having an electron gun 12 schematically and generally indicatedtherein. Any known electron beam or other charged particle generatingdevices may be utilized as is well known in the art. The electron beamtravels along a path or axis shown at 14. The chamber 10 is defined bythe Wall 16 which is spaced from another wall 18 thereby forming anintermediateV low pressure chamber 20.

The walls 16 of the chamber 10 terminate at their lower end in a taperedbeam emitting exit 24 having an aperture 26. The beam exits through theaperture 26 and is .intended to impinge upon a workpiece 28.

In order to control the pressure in the region of the aperture 26, it isdesirable t form some barrier between the atmospheric pressure in theregion of the workpiece 28, the relative low pressure chamber 20 and thesubstantial vacuum in the beam penetrating chamber 10. To this end anannular manifold 30 is supplied with relatively high pressure fluidthrough the conduit 32 for emission through a plurality of orifices 34and 36. As seen in FIGURE 4, the orifices 34 and 36 are positionedsubstantially tangential of the vortex region forming the secondarychamber 38. The multiplicity of orifices insures a uniform pressuredistribution around the vortex and the electron beam axis such that aconcentricity with respect to the beam is achieved. In other words, ifthe vortex were not properly centered, the lowest pressure core regionwould not coincide with the electron beam from its point of emissionfrom the aperture 26 to the workpiece 28.

FIGURES 2 and 3 illustrate preferred embodiments of the invention. Asseen in FIGURE 2, the beam aperture means 24 is surrounded by a collaror ramp 42 thereby forming a second aperture 44 surrounding the aperturemeans 24.

Since a high rate of diffusion is desired, the angle 0f the wall of theaperture means 24 may vary in the range of an included angle of morethan 60 but less than Also, to obtain acceptable low density over thebeam path 14, the minimum flow area formed by the walls 16 should begreater than 400 times the area of the beam orifice 36.

Of course this is speaking of the possible fiow being in a directionupstream of the beam since the beam generating chamber 10 has the lowestpressure of the device.

It should be noted that in the embodiment shown in FIGURE 2 the aperture26 is located upstream along the beam axis relative to the lower lip 50of the ramp 42. Tests have shown that although relatively more pumpingis required via the chamber 20 in this configuration, a lower pressureis experienced at the aperture 26 even though the beam length to theworkpiece is somewhat longer.

The modification shown in FIGURE 3 illustrates an arrangement wherebythe aperture 26 is substantially coincident with the lip 50 of the ramp42. In this configuration less pumping power is necessary as compared tothe FIGURE 2 configuration. Also the external beam length is somewhatless that that shown in FIGURE 2.

As a result of this invention, it is apparent that a very simple butefficient mechanism has been provided whereby out-of-vacuum working canbe produced with an electron beam device whereby the pressure betweenthe workpiece and the point of emission of the electron beam can besuitably controlled. With a device of this nature a minimum of airflowcan pass to the beam penetrating region to thereby maintain beamfocusing and intensity. A vortex device of Vthis nature in combinationwith an electron beam emitting device maintains the beam emissionaperture relatively clean of working contaminants.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described but may be used in otherways without departure from its spirit as defined by the followingclaims.

We claim:

1. A charged particle working device having a beam generating chamber,means in said chamber for generating a beam of charged particles, meansfor substantially evacuating said generating chamber to reduce thegaseous content thereof, aperture means in said chamber from which saidbeam may exit to a higher pressure region, aperture means including adiffuser section having its smaller area at the chamber exit and itslarger area upstream of the generated beam, said larger area beinggreater than 400 times the area of said smaller area, said chambersurrounding said aperture means and tapering away therefrom, wall meanssurrounding said ramp and extending downwardly away from said chamberbeyond said aperture means, said wall means forming a second chamberoutside said beam generating chamber and exposed on one side to theatmosphere, and means for introducing a fluid into said second chamberand substantially tangentially of said wall to produce a vortexsubstantially surrounding said aperture means.

2. A device according to claim 1 wherein said second aperture issubstantially aligned along the beam with respect to said aperture meansand concentric therewith.

.3. A device according to claim 2 wherein the means for introducingfluid into said second chamber includes a plurality of passages in saidwall means to insure uniformity of fiow distribution in said secondchamber and concentricity of the core of said vortex with respect to thebeam.

4. A device according to claim 3 wherein said ramp means includes asecond aperture surrounding said aperture means.

5. A device according to claim 4 wherein said second aperture isconnected to a relatively low pressure region below atmospheric.

6. A device according to claim 4 wherein said second aperture is spaceddownstream along said beam with respect t said aperture means.

7. A device having a vacuum chamber, means for sub stantially evacuatingsaid chamber to reduce the gaseous content thereof, aperture means insaid chamber which exits to a higher pressure region, wall meansradially spaced from and surrounding said aperture and extendingdownwardly away from said chamber beyond said aperture means, said wallmeans forming a second chamber outside said vacuum chamber, and meansfor intro` ducing a uid into said second chamber to produce a vortexsubstantially surrounding said aperture means.

8. A charged particle working device having a beam generating chamber,means in said chamber for generating a beam of charged particles, meansfor substantially evacuating said generating chamber to reduce thegaseous content thereof, aperture means in said chamber from which saidbeam may exit to a higher pressure region,

aperture means including a diffuser section having its smaller area atthe chamber eXit and its larger area upstream of the generated beam, aramp outside said chamber surrounding said aperture means and taperingaway therefrom, wall means surrounding said ramp and eX- tendingdownwardly away from said chamber beyond said aperture means, said wallmeans forming a second chamber outside said beam generating chamber andexposed on one side to the atmosphere, and means for introducing a fluidinto said second chamber and substantially tangentially of said wall toproduce a vortex substantially surrounding said aperture means.

References Cited UNITED STATES PATENTS 1,638,336 8/1927 Himes.

3,156,811 11/1964 Barry 219-121 3,162,749 12/1964 Peracchio 2l9-1213,171,943 3/1965 Niedzielski 219-121 3,175,073 3/1965 Niedzielski et al.219-121 3,217,135 11/1965 Eklund 219-121 RICHARD M. l/VOOD, PrimaryExaminer'.

W. D. BROOKS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE O "atent No. 3,388 ,235 y June11, 1965? Edward A. Pnsley et a1 It is certified that error appears inthe above identified patent and that said Letters Patent are herebycorrected as` shown below:

Column 2, line 63, claim reference numeral "1" shoul 1 :gi-CORRECTION t4 line 66, claim reference numeral "Z" should @ad s m.

Signed and sealed ti's-r'l4th day of November 1969.

SEAL) Lttest:

ldward M. Fletcher, Jr.

Lttesting Officer WILLIAM E. SCHUTLER,- f

Commissioner of Pa v

1. A CHARGED PARTICLE WORKING DEVICE HAVING A BEAM GENERATING CHAMBER,MEANS IN SAID CHAMBER FOR GENERATING A BEAM OF CHARGED PARTICLES, MEANSFOR SUBSTANTIALLY EVACUATING SAID GENERATING CHAMBER T REDUCE THEGASEOUS CONTENT THEREOF, APERURE MEANS IN SAID CHAMBER FROM WHICH SAIDBEAM MAY EXIT TO A HIGHER PRESSURE REGION, APERTURE MEANS INCLUDING ADIFFUSER SECTION HAVING ITS SMALLER AREA AT THE CHAMBER EXIT AND ITSLARGER AREA UPSTREAM OF THE GENERATED BEAM, SAID LARGER AREA BEINGGREATER THAN 400 TIMES THE AREA OF SAID SMALLER AREA, SAID CHAMBERSURROUNDING SAID APERTURE MEANS AND TAPERING AWAY THEREFROM, WALL MEANSSURROUNDING SAID RAMP AND EXTENDING DOWNWARDLY AWAY FROM SAID CHAMBERBEYOND SAID APERTURE MEANS, SAID WALL MEANS FORMING A SECOND CHAMBEROUTSIDE SAID BEAM GENERATING CHAMBER AND EXPOSED ON ONE SIDE TO THEATMOSPHERE, AND MEANS FOR INTRODUCING A FLUID INTO SAID SECOND CHAMBERAND SUBSTANTIALLY TANGENTIALLY OF SAID WALL TO PRODUCE A VORTEXSUBSTANTIALLY SURROUNDING SAID APERTURE MEANS.